This paper presents a robust and precise tension control method for a roll-to-roll (R2R) system. In R2R processing, robust and precise tension control is very important because improper web tension control leads to deterioration in the quality of web material. However, tension control is not easy because the R2R system has a model variation in which the inertia of the web in roll form is changed and external disturbances caused by web slip and crumpled web. Therefore, a disturbance observer (DOB) was proposed to achieve robustness against model variations and external disturbances. DOB is a robust control method widely used in various fields because of its simple structure and excellent performance. Moreover, the web passes through various process steps to achieve the finished product in the R2R process. Particularly, it is important to track the tension when magnitude of the tension varies during process. Feedforward (FF) controller was applied to minimize the tracking error in the transient section where tension changes. Moreover, the signal processing of a sensor using the Kalman filter (KF) in the R2R system greatly improved control performance. Finally, the effectiveness of the proposed control scheme is discussed using experimental results.

Recently, dual-motor driving steer-by-wire (SbW) systems have been introduced and have received considerable attention because they can overcome the limitations of single motor driving SbW systems, which cannot provide large torques required by commercial vehicles and are vulnerable to faults. The two main issues on the performance of the dual-motor driving SbW systems is to ensure steering robustness against model uncertainties, external disturbances, and road condition changes and to synchronize the steering angle. In this paper, a sliding mode controller (SMC) with a disturbance observer (DOB) under master-slave control is proposed to tackle these issues. The combination of an SMC and a DOB is employed to guarantee strong robustness against model uncertainties and external disturbances. In addition, masterslave control is applied to enhance the synchronization performance of dual motor driving SbW systems with significantly different dynamic and response characteristics. Comparative experimental studies are conducted to verify the excellent performance of the proposed control scheme for dual-motor driving SbW systems.

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